165121405 has 8 divisors (see below), whose sum is σ = 198232632. Its totient is φ = 132039168.

The previous prime is 165121403. The next prime is 165121423. The reversal of 165121405 is 504121561.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 23677956 + 141443449 = 4866^2 + 11893^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 165121405 - 2¹ = 165121403 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 165121405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165121403) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8337 + ... + 19993.

It is an arithmetic number, because the mean of its divisors is an integer number (24779079).

Almost surely, 2^165121405 is an apocalyptic number.

It is an amenable number.

165121405 is a deficient number, since it is larger than the sum of its proper divisors (33111227).

165121405 is a wasteful number, since it uses less digits than its factorization.

165121405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14495.

The product of its (nonzero) digits is 1200, while the sum is 25.

The square root of 165121405 is about 12849.9573929255. The cubic root of 165121405 is about 548.6151440695.

Adding to 165121405 its reverse (504121561), we get a palindrome (669242966).

The spelling of 165121405 in words is "one hundred sixty-five million, one hundred twenty-one thousand, four hundred five".